This invention generally relates to temperature control systems. More particularly, embodiments of this invention relate to devices for controlling temperature in a building, such as a HVAC system and/or a water heating system, wherein the estimated time to reach a target temperature is displayed to a user.
Building heating ventilation and air-conditioning (HVAC) systems account for a significant percentage of total energy consumption. Thus, a significant savings in HVAC energy usage can have an impact on total energy consumption. Programmable thermostats have been commercially available for many years and are used in many residential and light industrial settings. However, the typical user in the residential and light-industrial setting is relatively unsophisticated in terms of HVAC technology and efficiency. Despite the fact that HVAC energy use makes up a significant portion of total energy use in a residential or light industrial setting, a typical residential or light industrial occupant using a thermostat to manually input a set point or target temperature—either to increase the current temperature in the case of heating, or decrease the current temperature in the case of cooling—does not have a good understanding of how much energy is required to carry out the increase or decrease in temperature being called for. For example, a typical user does not have a good idea of how much energy it takes to raise the temperature of his or her dwelling by various amounts on a cold winter day. Some sophisticated thermostats are capable of calculating and displaying cost information associated with set point changes. For example, see U.S. Pat. No. 7,392,661, which discusses an HVAC system controller which estimates the energy cost or savings incurred due to a user-instigated change in a climate control schedule. Estimated costs or savings can be displayed to the user in an effort to give the user a basis for making decisions. However, it is believed that displaying costs and/or savings alone does not necessarily give many users a good awareness of HVAC system usage.